LI singer-songwriter Leslie Mendelson opened for The Who's MSG show

Those who arrived in time to see the opening act of The Who's Madison Square Garden concert Sunday may have asked the question posed by the iconic band's 1978 album: "Who Are You." The answer: Long Island native Leslie Mendelson, whose fans include none other than Who lead singer Roger Daltrey.

"He says I'm his go-to when he tours solo," the Port Jefferson-born and South Setauket-raised Mendelson, 41, told Newsday following her second Garden opening for The Who, after opening for their May show there. "I got to know Roger because I was managed by The Who's management when I lived in London [from 2012 to 2014], and Roger had me do a few dates last year  with his solo band,” including at the Hard Rock Hotel & Casino in Las Vegas. "So when it came time to do the New York shows, they just thought to ask me."

The singer-songwriter assures she is not as blasé about that as it may sound. "It's amazing!" she adds readily. "I was blown away!" Mendelson also not only toured with music great Jackson Browne throughout August, but he also co-wrote with her and her songwriting partner Steve McEwan the ballad "A Human Touch," which plays over the end-credits of the recent documentary "5B."

Oscar-winning filmmaker Paul Haggis ("Crash"), who co-directed that film about a San Francisco hospital's AIDS ward during the early days of that epidemic, was a guest of Mendelson's on Sunday, she says. So was her father, Alan Mendelson, a retired music teacher and a trumpeter who performs with the West Islip Symphony Orchestra, Sayville's Bay Area Symphony Orchestra and the Brentwood-based Island Symphony Orchestra.

"Apparently my dad shushed Matt Dillion during my set," chuckles Leslie Mendelson, who says the actor came as a guest of Haggis’. "He didn't know it was him! On the one hand I'm mortified, and on the other, 'Yeah, that's my dad!' “ Her mom, Geri Mendelson, a retired early-intervention service coordinator for children with special needs, and her younger sister Erin live on the West Coast.

Leslie Mendelson, now a Brooklyn resident, attended Ward Melville High School in East Setauket, followed by Suffolk Community College before leaving to study piano at the Brooklyn-Queens Conservatory. She released her debut album, "Take It as You Will," in 2005, then came under the mentorship of legendary producer Joel Dorn, who had guided the likes of Roberta Flack and Bette Midler to their first hits and helped sign Mendelson to the prestigious label Rykodisc.

Dorn's death in December 2007 devastated her, however. Combined with other setbacks, her second album, "Swan Feathers" took until 2009 to complete. There was an eight-year hiatus between that and her next, "Love and Murder." But her fourth album, "If You Can't Say Anything Nice…," is set for release early next year. 

"During the times when I wasn't touring a lot or having down times, I was lucky enough to do jingles and work on other people's records," says Mendelson, who performs regularly in the area and next gigs as part of Steve Kimock & Friends on Sept. 27 at (Le) Poisson Rouge in Greenwich Village. She is not sharing the bill with The Who on Sept. 15 at Jones Beach, where no opening act is listed for that show.

"There are so many artists out there finding ways to cut through," says the prolific performer. "As far as making it, I haven't had one major break, just a series of little breaks. Hopefully they'll keep coming."

For more on Leslie Mendelson, see her videos on YouTube.